Taz 5 Heat Sink Fan

I own a Lulzbot Taz 5, I have had it for approximately 2 months.

  1. I’ve had maybe a hundred+ good prints, a comparable number of failures, and an unfortunate amount of debilitating jams.
  2. I regularly level my print bed.
  3. I clean my extruder thoroughly, before and after jams.
  4. I keep my filament in a dry environment, practically swimming in little packs of silica gel.
  5. I regularly swap out the 3mm hot end for a hexagon 1.75mm hot end (purchased 3rd party) when the hot end currently in use jams up and I need to soak it in acetone to clean it out.
  6. Up until today, I have exclusively printed with ABS. (esun 3mm, hatchbox 1.75mm)
  7. I love my machine.

The above now established, I will move on to the “meat and potatoes” of my post.

The first time I powered on my machine and heated the hot end, a tiny puff of smoke come out of the heat sink fan. It seemed to be operating properly, and being engrossed in the setup process and general excitement of getting started, I mindlessly thought nothing of it. I proceeded to use my machine with varying success for about a month.

One day, while soaking my hot end in acetone to clear out a jam, I began searching the forum for posts regarding whether or not it was possible to utilize 1.75mm filament with the stock hot end. I stumbled upon a few threads that suggested it was possible. Having received a 3d printing pen as a gift a couple months prior to ordering my machine, I had a few rolls of 1.75mm filament handy and decided to give it a try. The filament buckled just past the hobbed bolt every time, and after a weekend of tinkering with it, I ended up ordering a 1.75mm hexagon hot end kit from a 3rd party website. I have been using it with the same varying rate of success as my 3mm hexagon. Only swapping out the hot end, still using the stock heater and thermistor.

Today, (after a jam in my 1.75mm hot end) I reattached my 3mm hotend and decided to try my luck printing with a roll of esun 3mm PLA that I had received about a week prior. This being my first attempt at printing with PLA, I was discouraged with the amount of trouble I’ve had. The extruder leaks so much that I have been unable to print even a 20mm cube without the extruder jamming.

Every time I either:

  1. insert filament into the pre-heated hot end, or
  2. slowly heat the hot end with filament inserted and then manually (from pronterface, or by hand) extrude some filament to get the end primed:

A vast quantity of filament rapidly leaks out of the nozzle. From what I can tell, this results in two things:

  1. a cavity of air forms between the opening at the hobbed bolt and the nozzle, and / or
  2. the nozzle ends up with either a giant glob of PLA stuck to it, entirely coated in PLA, or jammed up altogether.

I tried the following to remedy the leaking:

  1. altering Slic3r retraction settings, trying a number of configurations
    –a) did not expect this to solve the problem, as the leaking occurred constantly. Not just when printing
  2. replaced the stock thermistor with the one that came with my 1.75mm kit
    –a) thought maybe the stock thermistor was malfunctioning and the hot end was going past the ~205c I was setting it at

Neither of these things solved the problem.

I got my hands on an infrared thermometer and everything became clear to me. With my hot end set at 205c, the heat sink just below the mounting plate was reaching ~160-170c. Heat is creeping up my hot end assembly.

I am now reminded of the tiny puff of smoke that came from my heat sink fan at the time of my initial set up and I am inclined to believe the fan has not been operating consistently since.

I am hoping that this is the source of the issues I have been experiencing, as replacing a fan sounds a lot easier than everything else I’ve been doing.

Hoping I can get my hands on a replacement heat-sink fan.

You’re best bet is to contact Lulzbot support. The little blowers are hard to find.

The other option is to use the heatsink duct that came with your 1.75 hexagon and find a suitable 5v box fan.

The 1.75 hexagon did come with a 5v box fan, but unfortunately no duct or any apparent way to mount it.

I cleaned the PLA jam out of my 3mm hexagon this morning with a power drill, very carefully. I first used a 1/8 inch bit to clean out the PLA from the top opening to the beginning of the threaded tube into the heater block. I then used a 5/64 inch bit to bore about .5cm into the PLA which was occupying the tube and heater block down to the nozzle. I then slowly backed the bit out of the hot end with the piece of PLA stuck to the end it. Pictures are in the link below.

This afternoon I contacted LulzBot Support, they’re going to be sending me a replacement fan. But in the meantime, I found this duct http://www.thingiverse.com/thing:439772 and successfully printed it with the 3mm hexagon using ABS, without a heat-sink fan. I’m in the process of attempting to attach the 3rd party 5v box fan using this mount. I don’t particularly like the design and that it has direct contact with the heat-sink, so I may just opt to not print PLA until I get the stock fan from LulzBot. See the link below for pictures of the print.

Pictures can be found here: https://drive.google.com/folderview?id=0B5mLvFXpHPRCRkVIQ2pJSzJoeUk

Hmm… interesting. Just checked my 1.75mm hexagon kit from Amazon, and it doesn’t have a duct for the box fan. The 3mm (also from Amazon) has the duct that slides on the fins. Nice find on the Thingiverse duct… guess I’ll need to print one. :slight_smile:

I use drill bits to help with cleaning also… nailing the 1/8 pilot is the key. :slight_smile: Looking at your pictures, I just realized you’re soaking the whole hotend in acetone. I usually wrench off the nozzle (heat hotend to 165C) to soak. But I guess the heat creep is bad, the only way to unclog the hotend above the heater is to soak the entire thing or drill. I think they use some sort of loctite on the heatbreak.

Don’t print it! It didn’t fit. : (

The end that attaches to the hot end needs to be made more narrow, so that it doesn’t clash with the extruder assembly.

Ahhh… I see. The end that wraps around the… bummer. I wonder if the duct from my 3mm kit wraps too far around also… Could explain the littlel blower assembly that LB uses.

Well, I just released my new heat sink fan shroud mod for Taz + Hex hot end:

If you are handy, you should be able to put it together in about a half hour after printing the parts (once you have all the goods on hand that is).